Rarely has such squealing been heard in the corridors of the Capitol when the 28-year-old third-in-line to the British throne turned up for a visit Thursday.

And then more squealing when he appeared at a White House tea party for an unexpected drop-in with a crowd of stunned military moms and grandmoms.

Prince Harry meets U.S. Army Col. Gregory Gadson at a dinner at the British Embassy.(Photo: Alex Brandon AFP/Getty Images)

And he topped it off with a glittering, sweltering, intimate gathering of American VIPs at a reception and dinner at the British Embassy. No signs of jet lag but he might feel it early Friday when he pays a somber visit to Arlington National Cemetery.

But Thursday was mostly about the festive, and never mind Washington's typical humidity, although Harry was seen to wipe his brow at the reception this evening. Earlier, he was the one who caused women to feel faint and children to squeal.

Prince Harry talks with kids at White House party for military families.(Photo: Mark Wilson Getty Images)

"Well, surprise!" exclaimed first lady Michelle Obama, co-hosted by second lady Jill Biden at the White House party, as tables of women and kids clapped and cheered and Harry blushed and grinned beside her.

Harry arrived at Dulles International Airport Thursday afternoon on a commercial flight from London for the first day of a week-long visit to the USA to promote Britain, raise money for charity and cheer on wounded veterans.

He's here! Britain's Prince Harry arrived in the USA in style on May 9, making a quick trip from Washington Dulles Airport to Capitol Hill for the first leg of his stateside tour. Here, the young royal is greeted by U.S. Senator John McCain, R-Ariz., as he arrives at the Russell Senate Office Building to visit a photo exhibition on land mines and unexploded ordinance. (Photo: MANDEL NGAN, AFP/Getty Images)

Prince Harry and Sen. John McCain, R-Ariz., depart the Russell Building as the prince makes his way to the White House for a surprise visit with first lady Michelle Obama. (Photo: Mandel Ngan, AFP/Getty Images)

Prince Harry has a reputation of being good with kids, and he seemed to show it at the White House party for military families. Accompanied by first lady and co-host Michelle Obama, Harry got up close and personal with some of the little guests. (Photo: Mark Wilson Getty Images)

A good time was had by all. First lady Michelle Obama, Prince Harry and Jill Biden have plenty to grin about during Harry's surprise appearance at a party for military families in the State Dining Room of the White House. (Photo: Jacquelyn Martin AP)

Harry has made supporting wounded warriors a special cause, so he's pleased to meet U.S. Army Col. Gregory Gadson at a reception at the British Embassy. Gadson is a double-amputee who was injured in 2007 in Iraq. (Photo: Alex Brandon AFP/Getty Images)

Prince Harry is flanked by Teresa Heinz, wife of Secretary of State John Kerry, and Lady Westmacott, wife of the British ambassador to the U.S., at dinner. That's U.S. Sen. John McCain next to her. (Photo: Jim Lo Scalzo AFP/Getty Images)

Prince Harry, in full dress British Army uniform, participates in solemn and colorful ceremonies at Arlington National Cemetery, surrounded by a huge but respectful crowd, on the second day of his USA visit. (Photo: Arienne Thompson)

Prince Harry, wearing his ceremonial uniform of The Blues and Royals, salutes as he pays his respects to war dead at Arlington National Cemetery on second day of his USA visit. He was accompanied by Major General Michael Linnington. (Photo: Chris Jackson Getty Images)

Prince Harry places a wreath at the Tomb of the Unknowns in Arlington National Cemetery, the traditional ceremony for visiting VIPs, especially serving military such as Harry, a captain in the British Army. The wreath is made of poppies, the symbol of WWI that Brits and Europeans wear every November 11. (Photo: Brendan Smialowski AFP/Getty Images)

Wonder if that curtain behind him was deliberate? Harry gives a speech at the embassy dinner, about land mines and the Halo Trust, which works to clear them from war-torn parts of the world. His mother, Princess Diana, was the royal patron before she died and now Harry has taken on the job. (Photo: Alex Brandon AP)

Wearing his British Army camouflage, Prince Harry visits Staff Sgt. Timothy Payne, who lost his legs in an IED explosion in Afghanistan, at Walter Reed National Military Medical Center in Bethesda, Md, where he is one of scores of wounded warriors undergoing physical therapy. Harry has made support for wounded vets one of his special causes. (Photo: J. Scott Applewhite AP)

Prince Harry meets with members of the British team of wounded warriors competing at the Warrior Games in Colorado Springs. As a British Army captain, he's wearing his army fatigues and desert boots. (Photo: Pool, Getty Images)

Prince Harry speaks to British hand-cycling competitor before the start of the race at the U.S. Air Force Training Academy in Colorado Springs, on Sunday, his second day at the Warrior Games and the fourth day of his week-long visit to the USA. (Photo: Chris Jackson, Getty Images)

How's his form? Prince Harry tries throwing an American football at the U.S. Air Force Academy's football training center during the Warrior Games in Colorado Springs. He'll have a go at baseball, too, as he continues his visit to the USA. (Photo: Pool Getty Images)

Of course, wherever Harry goes, royal watchers follow. Here, Terri Bissell, left, a resident of Seaside Heights for 12 years, calls to tell a relative that the prince has been sighted, while Tom's River resident Andrea D'Anton, tries to take his picture at Casino Pier on the newly rebuilt boardwalk. (Photo: Denny Gainer, USA TODAY)

That evening, Prince Harry suited up and shook hands with John Studzinski, the president of the American Friends of The Royal Foundation during a fundraiser for the organization. (Photo: Jason DeCrow, AP)

Naturally, Harry's team won the charity match! He and his teammates Michael Carrazza, left, Malcolm Borwick and Mark Ganzi celebrated their victory while checking out their trophy. (Photo: Craig Ruttle, AP)

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He headed first to Capitol Hill to see an exhibit on clearing land mines (a cause dear to heart of his late mother, Princess Diana), accompanied by Sen. John McCain, R-Ariz. (His wife, Cindy McCain, is on the board of Halo Trust, the anti-land mine charity that organized the exhibit in a Senate office building, but she was unable to make it due to an injury. She was "heartbroken," her husband said.)

While touring the exhibit, Harry was interested and animated and flashed many broad smiles. Every time the crowd outside of the rotunda caught a glimpse of him through the arches, cheers echoed in the space.

McCain was impressed. He told reporters later that Harry was charming, funny and genuinely interested in land mine clearance (he's now the royal patron of the group). He asked in-depth questions, not just "cosmetic" ones, McCain said. He said he and Harry joked, in the time-honored way, about rivalries between the army and the navy (Harry is a British Army aviator and McCain was a naval aviator and POW during the Vietnam War), and compared notes about their respective aircraft (Harry flies the same Apache helicopters as McCain's son, the senator said).

McCain was especially amused at the reaction of the crowd to Harry. "I've never seen in all my years here such a one-gendered crowd," he joked.

Next, Harry made a surprise visit to the White House where he met Michelle Obama, who was co-hosting a Joining Forces event in honor of military mothers. As has Harry, the two women have made supporting military families a signature cause.

"Prince Harry wanted to be here to personally thank you for your service," she told the moms and grandmoms at the party. He greeted as many as possible before leaving for the reception and dinner for 37 at the embassy, where he gave a speech on landmines.

The BBC's Peter Hunt tweeted that Princess Diana would be "so proud" he's taken up the patronage of the land mines charity, the Halo Trust.

On Friday, Harry will lay a wreath at Arlington, and visit wounded vets at Walter Reed National Military Medical Center. He'll then fly to Colorado to cheer on veterans at the Warrior Games over the weekend in Colorado Springs. Next week he will tour Hurricane Sandy damage in New Jersey with Gov. Chris Christie, promote British tourism and attend a charity fundraiser in New York, and play in a polo match in Greenwich, Conn., to raise money for his African children's charity.

Some parts of the Twitterverse were all aflutter awaiting Harry's arrival Thursday.

"The definitive guide to stalking Prince Harry during his visit to America," read one tweet. "My Prince Harry senses are tingling. Happy that the world's most eligible bachelor is in the good ol' US of A," read another.

Harry's visit comes as his grandmother, Queen Elizabeth II, 87, has finally started cutting back on her busy round of public appearances and turns to her heir, Prince Charles, and his sons, Harry and Prince William, 30, to take up more royal duties in her place.

It also comes in the wake of Harry's hugely successful tour of the Caribbean and Latin America last year, and those embarrassing photos of him playing pool while nude in a Las Vegas hotel room that he and the rest of the Windsors would love to forget. Chances of a repeat on this trip? Zip.